Annelid Worms Flashcards

Study Notes

Examples of Annelid Worms

Common examples include the leech, earthworm, and members of the class Clitellata.

Characteristics of Annelid Worms

Leeches belong to the class Clitellata and sub-class Hirudinea under the Phylum Annelida.
They exhibit a segmented, worm-like body that is flattened dorsoventrally with suction disks at both ends.
The posterior sucker serves to anchor the leech in place.

Reproduction in Annelid Worms

Leeches are hermaphrodites, possessing both male and female reproductive organs.
During mating, sperm is transferred between individuals and stored in sacs.
The clitellum produces mucus that immobilizes the worms during copulation.

Metamorphosis in Annelid Worms

Leeches undergo epimorphic development, meaning growth occurs without significant changes in form.
Earthworms develop directly without metamorphosis.
Clitellata may have an aquatic larval stage that undergoes metamorphosis to become radically different adult forms, although reproductive strategies can vary.

Respiration in Annelid Worms

Leeches lack lungs and respire through their skin.
Earthworms similarly absorb oxygen and expel carbon dioxide directly through their skin without lungs.
All members of Clitellata breathe via their skin rather than through lungs.

Circulatory System of Annelid Worms

Most leeches possess a closed circulatory system, while some have an open circulatory system where blood is not enclosed in vessels.
Earthworms have a fully closed circulatory system, circulating blood exclusively through vessels including aortic arches, dorsal, and ventral blood vessels.

Fun Facts About Annelid Worms

Leeches prefer habitats like marshes, rivers, and ponds; roughly 20% inhabit marine environments.
The species Hirudo medicinalis is widely recognized as the medical leech.
There are roughly 2,700 species of earthworms, thriving in nutrient-rich, moist environments.
An acre of land can host over a million earthworms.
Clitellata is a diverse class comprising approximately 8,000 species, distinguished by the presence of a clitellum that forms a reproductive cocoon.

Description

This quiz provides flashcards on annelid worms, focusing on examples like leeches and earthworms, as well as their shared characteristics. Enhance your knowledge of the Class Clitellata and sub-class Hirudinea within the Phylum Annelida.